The goal of this project is to improve our knowledge of the mechanisms used by F. virguliforme to cause SDS. We will address this goal by studying how a toxin secreted by F. virguliforme affects SDS foliar symptoms, and by testing the roles of selected F. virguliforme genes on symptom development. Information from the toxin studies will help to explain the sources of variation in symptom expression observed in SDS and potentially identify sites of toxin resistance. The identification of F. virguliforme genes that contribute to SDS symptom development is likely to provide insight into the biochemical functions of their products, and to enable future detailed studies on how they damage soybean....